This is where a new breed of cell phone "concierge" service using trusty text message technology comes in handy.

Several operators have launched in recent months, claiming they can answer any question sent by simple SMS -- the short message service supported by virtually all cell phone networks.

In the U.S., these have now begun directly targeting business travelers following a deal between car rental firm Avis and mobile information providers AskMeNow.

The question-answering services claim to be able to respond to any query from "why is the sky blue?" to more complex requests about hotels, transport or directions.

Among those offering text message services is leading Internet search engine Google, which provides U.S. cell phone users with help in the shape of directory listings, movie times, stock prices and even the locations of local pizza restaurants.

In Australia, the Mojoknows service claims it will answer any question by text message within 15 minutes. In the UK, AQA (short for "any questions answered") says it can do it in six. Users pay for the service with charges on their phone bill.

AskMeNow CEO Darryl Cohen said his firm's service, retailing at 49 cents an answer and drawing responses from a call center based in the Philippines, offers an indispensable resource for executives on the move.

Surge in sex questions

"By providing responses to virtually any question at any time from any location, AskMeNow is the ultimate business resource for any business person on the road," he said.

But these bold claims have raised the eyebrows of skeptics who have tried to stump the services with a particularly tough line of questioning.

The New York Times put AskMeNow on the spot with the poser: "Does Franklin Delano Roosevelt deserve credit for ending the Depression?''

It received "an extensive but noncommittal response ... beginning, 'President Franklin Roosevelt's New Deal fought the Great Depression on a number of fronts.'''

In the UK, the AQA service seems to have attracted a more salacious line of inquiry, reporting a significant surge in sex-related questions shortly before 11 p.m.